The present application relates to insertion instruments, in particular surgical insertion instruments, for insertion into a cavity, in particular in a human subject, as well as to systems comprising such instruments.

So called "growing robots" have been known for various fields of applications. Such a robot is known from US 2019/0217908 A1 which discloses an everted tubular sheet whose inner portion is wound up on a reel. By unwinding the tubular sheet from the reel and blowing a gas into a chamber enclosed by the sheet, the length of an outer portion of the sheet can be increased. Howev er, when the sheet has been introduced into a cavity, the pres sure inside the chamber usually prevents the insertion of any other device through the robot and into the cavity. Instead, in order to avoid piercing the sheet, the growing robot must be fully deployed or depressurized to allow the insertion of anoth er device through a passage formed in the growing robot. Moreo ver, the instrument does not allow the removal of gases or liq uids from the cavity.

US 2003/0168068 A1 discloses an instrument which can be used for medical purposes. The instrument is based on an everted tubular sheet. In one embodiment, an inflatable tubular sheet is ar ranged in such a way that an endoscope can be entered through a passage formed inside an inner portion of the sheet. However, since the inner portion is only loosely wrapped up in an initial state, the extension cannot be precisely controlled. Moreover, the process cannot be reversed so that the instrument cannot be easily retracted from the cavity.

Moreover, US 5,236,423 discloses a tubular sheet whose inner portion is gathered in an initial state. This sheet has the same disadvantages, i. e. the extension cannot be precisely control- led, and the process cannot be reversed so that the instrument cannot be easily retracted from the cavity.

It is an object of the present application to provide an instru ment in which at least some of the disadvantages mentioned above are overcome. In particular, it should allow a controlled re lease of the tubular sheet and the insertion of a device such as a surgical, therapeutic or diagnostic instrument or a sensor and simplify the retraction of the instrument.

In a first aspect of the invention, this is achieved by an in sertion instrument, in particular a surgical insertion instru ment, for insertion into a cavity, in particular a cavity of a human subject. The instrument comprises

- a flexible tubular sheet having a first annular end, a second annular end and a middle section extending between the first annular end and the second annular end,

- a first holding member holding the first annular end, wherein an outer tubular portion of the middle section extends along an extension direction, from the first holding member to a distal tip of the instrument,

- a second holding member holding a tubular inner portion of the middle section, wherein the inner portion extends inside the outer tubular portion of the sheet, from the second hold ing member to the distal tip, the inner portion transiting into the outer portion at the distal tip,

- a passage defined inside the inner tubular portion of the sheet, which passage extends from the second holding member and opens out at the distal tip.

As already mentioned, the insertion instrument may be a surgical insertion instrument that can be inserted into a cavity of a hu man subject. For example, it may be used to explore and perform procedures on the upper gastrointestinal tract, in particular esophagus, stomach, and/or small intestine, the lower gastroin- testinal tract, in particular colon and/or rectum, the biliopan- creatic tract, in particular common bile duct, intrahepatic bile ducts, cystic duct, and/or Wirsung canal, the urinary tract, in particular calyces of the kidney, ureter, bladder, and/or ure thra, the respiratory tract, in particular trachea, bronchi, and/or bronchioles, the uterine cavity, the Fallopian tubes, the nasal cavities, the maxillary sinuses, the frontal sinus, the Eustachian tubes, the tear ducts, the brain ventricles, the cen tral canal of the spina medulla, the mesencephalon aqueduct and the vessels.

However, the invention also encompasses insertion instruments which are adapted and can be used for non-medical purposes, such as for insertion into tubular structures of any kind, e. g. in dustrial tubes whose interiors have to be inspected, for example with the aid of a camera that can be introduced through the pas sage of the insertion instrument.

The distal tip is arranged in an area where the tubular sheet is everted. As will become clear from the exemplary embodiments, the inner portion and the outer portion hence dynamically change during the process of inserting the instrument. Moreover, the distal tip is not fixed but changes its location during use of the instrument. Hereinafter, the outer tubular portion and the inner tubular portion will sometimes together be referred to as the extension of the instrument. As will also become clear from the exemplary embodiments, the tubular sheet may be bent active ly or passively during the process. In a bent state, the exten sion direction is to be understood as a local direction which changes along the extension.

A chamber may be formed which is at least partially enclosed by the inner portion of the sheet and the outer portion of the sheet. A fluid, which may be a gas or a liquid, can be intro duced into the chamber in order to extend the device. When the sheet is at least essentially fluid-tight, controlling a fluid pressure inside the chamber can press the outer portion of the sheet against an interior wall of a cavity into which the in strument is inserted. Additionally, the length of the extension can be controlled at least in part by the fluid pressure and the amount of fluid inside the chamber.

As will be further explained, an interior device may be inserted through the passage defined inside the inner tubular portion, in particular a surgical, therapeutic or diagnostic instrument, a sensor, a robot (in particular an autonomous robot or a magneti cally guided robot), a camera or a drug delivery system. The drug delivery system may be suitable for delivering drugs, for example encapsulated drugs.

The passage may also be advantageous for additional uses. It may serve as a channel or it may provide space for placing an addi tional channel or lumen. Such a channel may e.g. be useful for preserving a blood circulation through the insertion instrument, e.g. when inserting the instrument into a cerebral artery. It may allow carrying a fluid (gas or liquid) or to add or remove substances or material through the insertion instrument.

It may e.g. allow a suction of matter through the same, for ex ample a thrombus during thrombectomy. It may also be used for removing a sample taken during a biopsy.

The instrument may also comprise an additional lumen arranged or arrangeable within the passage. The additional lumen has an open distal end. Its proximal end may e.g. be connectable to a suc tion port in case of uses for thrombectomy. It may also lead to a vessel such as to allow blood flow from the proximal to the distal end.

In accordance with a first aspect of the invention, the length of the outer portion of the sheet along the extension direction can be controlled by moving the inner portion of the sheet by means of the second holding member. For example, the motion of the inner portion may be controlled via driving and/or via brak ing the second holding member. Preferably, the inner portion of the sheet is actively moved.

The second holding member is preferably designed and arranged to hold open the passage, in particular also in a bent state of the extension. This allows the insertion of an interior device, in particular a surgical, therapeutic or diagnostic instrument, a sensor, a robot, a camera or a drug delivery system.

The diameter of the passage may be chosen in accordance with the specific application of the device. For instance, suitable diam eters for endovascular applications may lie in the range from 2 mm to 5 mm, while they may lie in the range from 5 mm to 25 mm for endoscopic applications.

Preferably, the second holding member comprises a winding device for winding up the inner portion of the sheet. This arrangement provides a small overall size of the second holding member.

The inner portion may be evertingly woundable about itself by the winding device. Therefore, when wound, a radial inner sur face of the inner portion lies against a radial outer surface of the inner portion.

The winding device may comprise at least one driving wheel which is rotatable about a driving axis that is arranged transversely (i. e. at a non-zero angle) with respect to the extension direc tion, in particular perpendicular to the extension direction.

The driving wheel may be mounted on a ball bearing or bushing and may be motorized by a motor. Brushless DC motors are espe cially suitable as they avoid noise and dust emission. The driv ing wheel and/or the motor may be forced against an inner or an outer surface of the inner portion of the sheet by at least one spring to ensure an even pressure as the thickness of the wound up portion of the sheet changes. The winding device preferably comprises at least two such driv ing wheels, wherein different circumferential portions of the inner portion of the sheet are in contact with respective driv ing wheels. This allows a more even winding up.

With further preference, the winding device also contains at least one positioning device which is designed and arranged such that the inner portion of the sheet is held in position between the at least one driving wheel and the positioning device. The positioning device may comprise at least one positioning wheel which is designed and arranged such that the inner portion of the sheet is held in position between the at least one driving wheel and the at least one positioning wheel. The positioning device, in particular the positioning wheel, may also be biased against the sheet by at least one spring. Such an arrangement with a winding device with a driving wheel and optionally a po sitioning wheel may also be advantageous for driving other grow ing robot devices, e. g. not necessarily having a passage as de scribed above.

As an alternative to winding, the inner portion of the sheet may also be folded in order to control the length of the outer por tion of the sheet.

The sheet is preferably made from a material that is essentially not stretchable; otherwise the sheet would rather stretch than evolve when it is inflated. The sheet may be made of a plastic film, for example LDPE or LLDPE, or it may be constituted as a coated fabric. It may also be 3D printed with flexible resins.

In a second aspect of the invention, the instrument also com prises, as in the first aspect,

- a flexible tubular sheet having a first annular end, a second annular end and a middle section extending between the first annular end and the second annular end, - a first holding member holding the first annular end, wherein an outer tubular portion of the middle section extends along an extension direction, from the first holding member to a distal tip of the instrument,

- a second holding member holding a tubular inner portion of the middle section, wherein the inner portion extends inside the outer tubular portion of the sheet, from the second hold ing member to the distal tip, the inner portion transiting into the outer portion at the distal tip,

- a passage defined inside the inner tubular portion of the sheet, which passage extends from the second holding member and opens out at the distal tip.

In particular, the instrument may be designed as explained above.

According to the second aspect of the invention, the instrument further comprises at least one axially extendable stabilizing structure arranged inside the inner portion of the sheet in such a way that the inner portion of the sheet is prevented from closing the passage. The stabilizing structure may extend to the same extent as the outer tubular structure, thereby preventing the passage from closing, which facilitates the insertion of an interior device, in particular a surgical, therapeutic or diag nostic instrument, a sensor, a robot (in particular an autono mous robot or a magnetically guided robot), a camera or a drug delivery system.

The stabilizing structure may comprise a plurality of stabiliz ing rings which are arranged along the extension direction and, in particular, concentrically around a center line of the exten sion. Alternatively, the stabilizing structure may comprise at least one helical spring which extends along the extension di rection and, in particular, surrounds a centerline of the exten sion. The stabilizing rings or coils of the helical spring, respec tively, may be connected to one another by at least one, prefer ably several controlling wires extending in the extension direc tion. Preferably, the at least one controlling wire extends through openings provided in the stabilizing rings or coils of the helical spring, respectively. By pulling or releasing the controlling wire at a proximal end of the instrument, the length of the extension can be controlled. Moreover, when several di rection wires are present, the direction of a further eversion of the sheet at the distal tip can be controlled by selectively pulling or releasing the controlling wires at the proximal end of the instrument.

The helical spring and the controlling wires may be made of a metal, as for example nitinol or steel, or a plastic material. With preference, the controlling wires are essentially non elastic in order to prevent a backlash.

The instrument may contain more than one stabilizing structure, as for example three helical springs. Each stabilizing struc tures may have a respective centerline extending along the ex tension direction, wherein the centerlines may be arranged ex- centrically with respect to a centerline of the extension.

In particular, when there are several stabilizing structures, inside at least one or all stabilizing structures, a respective additional fluid-tight tubular sheet may be arranged which is closed at a distal end of the stabilizing structure. These addi tional sheets are distinct from the tubular sheet and arranged inside the inner portion of the latter. By selectively control ling the fluid pressures inside the tubular sheets, the direc tion of a further eversion of the sheet at the distal tip can be controlled .

With further preference, the distal tip comprises a tip head which is attached to the stabilizing structure and arranged out- side a chamber that is at least partially enclosed by the inner portion of the sheet and the outer portion of the sheet, wherein the tip head comprises a head opening forming a distal end of the passage. The tip head may add to the stability of the in strument at its distal tip.

The tip head may further comprise at least one measuring device for measuring a property of an inspected object inside a cavity, in particular at least one camera and/or at least one ultrasound probe. Other types of sensors such as pressure sensors, tempera ture sensors, optical sensors, e. g. for spectroscopic purposes, or electric or magnetic sensors are conceivable. Wires can be used to supply these measuring devices with energy and/or to transmit data measured by the measuring devices. The wires can be arranged, for example, along the controlling wires mentioned above. Alternatively, the wires may be arranged inside one of several helical springs whose centerlines are arranged excentri- cally with respect to a centerline of the extension.

The distal tip of the instrument may comprise at least one guid ing wheel for guiding the sheet at its transition from its inner portion to its outer portion, wherein the guiding wheel is ar ranged inside the chamber that is at least partially enclosed by the inner portion of the sheet and the outer portion of the sheet.

Furthermore, the distal tip may comprise at least two, in par ticular four, guiding wheels which are rotatably arranged on a guiding ring that surrounds the passage. These guiding rings can aid the eversion of the sheet at the distal tip of the instru ment.

The guiding wheel may be passively driven due to the evolving movement of the sheet between the guiding wheels and the tip head. Alternatively, the at least one guiding wheel may be ac tively driven, which further facilitates the eversion of the sheet at the distal tip of the instrument. Electrical power sup ply to the guiding wheels may be achieved through wires which can be arranged, for example, along the controlling wires men tioned above or inside one of several helical springs whose cen terlines are arranged excentrically with respect to a centerline of the extension.

In a further aspect, the invention also relates to a set com prising an insertion instrument as disclosed above as well as at least one interior device provided for extending through the passage of the insertion instrument. In particular, the set may be a surgical set. The interior device may be a surgical, thera peutic or diagnostic instrument, a sensor, a robot (in particu lar an autonomous robot or a magnetically guided robot), a cam era or a drug delivery system. The invention also refers to the use of a lumen formed within the passage of the insertion in strument for a carrying a fluid such as a suction fluid, e.g. during thrombectomy or as a transport channel, e.g. for trans porting a biopsy sample during biopsy.

The invention will now be further explained with several embodi ments which are shown in the following figures. While these in sertion instruments are all embodied as surgical insertion in strument, the invention also encompasses non-surgical insertion instruments. In the drawings,

Figures la and b show a first inventive embodiment of an in- sertion instrument in a perspective view;

Figure 2 shows a helical spring of the first embodi ment in a perspective view;

Figure 3 shows the first embodiment in a sectional side view;

Figure 4 shows a second inventive embodiment of an insertion instrument in a sectional side view; Figure 5 shows a tip head of the second embodiment in a perspective view;

Figure 6 shows a third inventive embodiment in a straight state, in a perspective view;

Figure 7 shows the third embodiment in a bent state, in a perspective view;

Figure 8 shows a spring and an associated additional tubular sheet of the third embodiment;

Figure 9 shows a stabilizing structure of a fourth inventive embodiment in a perspective view;

Figure 10 shows a fifth inventive embodiment in a side view;

Figures 11a and b show an inventive embodiment of a surgical set comprising an insertion instrument and an surgical or diagnostic instrument.

The surgical insertion instrument 50 shown in Figures la to 3 comprises a base member 24 and a fluid-tight flexible tubular sheet 1. The sheet 1 is only shown in Figure la but hidden in Figure lb in order to more clearly display the remaining parts of the instrument 50.

The sheet 1 has a first annular end 12 that is fixed to the base member 24 which thereby forms a first holding member in terms of the present invention. The sheet 1 further comprises a second annular end 13 and a middle section 14 extending between the first annular end 2 and the second annular end 13. An outer tub ular portion 16 of the middle section 14 extends along an exten sion direction D, from the base member 24 to a distal tip 7 of the instrument 50 where it transits into an inner tubular por tion 18 arranged inside the outer tubular portion 16. The inner portion 18 and the outer portion 16 of the sheet 1 partially en close a chamber 25 in which a fluid, in particular a gas, can be inserted. The base member 24 encloses a cavity 27 that is fluid ly connected to the chamber 25. The base member 24 further con tains a fluid inlet 26 through which the fluid can be entered into the cavity 27 and into the chamber 25.

Inside the cavity 27, two driving wheels 5 are arranged which are rotatable about a respective driving axis A (see Figure 3) that is perpendicular to the extension direction D. The inner portion 18 of the sheet 1 is evertingly wound around itself, wherein different circumferential portions of the inner por tion 18 of the sheet 1 are in contact with the driving wheels 5. The driving wheels 5 are motorized by motors (not shown) and can therefore control the length of the inner portion 18 of the sheet 1.The inner tubular portion 18 of the sheet 1 defines a passage 19 which extends from the driving wheels 5 and opens out at the distal tip 17. As can be recognized, the driving wheels 5 are designed and arranged to hold open the passage 19.

The winding device also contains four positioning wheels 32 which are arranged such that the inner portion 18 of the sheet 1 is held in position between the driving wheels 5 and the posi tioning wheels 32. The motors are forced against the inner por tion 18 of the sheet 1 by springs 33 (not shown in Figure 3) to ensure an even pressure as the thickness of the wound-up portion of the sheet 1 changes.

A helical spring 12 is arranged inside the inner portion 18 of the sheet 1. A proximal end 23 (see Figure 3) of the spring 20 is fixed to the base member 24 of the instrument 50. It substan tially extends along the extension direction D. As best seen in Figure 2, the coils 21 of the spring 20 are loosely connected to one another by controlling wires 22. The controlling wires 22 also extend in the extension direction D and through openings 29 provided in the coils 21 of the spring 20. The spring 20 provides a stabilizing structure which prevents the sheet 1 from closing the passage 19. This in turn allows a surgical instrument or a sensor to be inserted through the pas sage 19, even when the sheet 1 bends. Also, a lumrn is formed or the passage can be used to place an additional, separate lumen. The lumen is useable for various purposes, e.g. for allowing blood flow, for carrying a fluid for suction, e.g. for removing a thrombus during thrombectomy or for carrying a biopsy sample. By pulling or releasing the controlling wire 22 at a proximal end of the instrument 50, the length of the extension can be controlled. By selectively pulling the controlling wires 22 at a proximal end of the instrument 50, even the direction of further eversion of the sheet 1 at the distal tip 17 can be controlled.

The distal tip 17 of the instrument 50 comprises a tip head 4 which is attached to the spring 20 and which is arranged outside the chamber 25. The tip head 4 further comprises a head open ing 7 forming a distal end of the passage 19 as well as two cam eras 8 and an ultrasound probe 9. The cameras 8 and the ultra sound probe 9 may be supplied with energy through supply lines that may extend through the openings 29.

In the second embodiment shown in Figures 4 and 5, the distal tip 17 of the instrument 50 further comprise a guiding ring 28 carrying four guiding wheels 6 which are all arranged inside the chamber 25. They serve the purpose of guiding the sheet 1 (not shown in Figures 4 and 5) between the tip head 4 and the guiding wheels 6, at its transition from its inner portion 18 to its outer portion 16.

A third embodiment is displayed in Figures 6 and 7. For the pur pose of simplifying the drawings, the positioning wheels and springs are not shown in Figures 6 and 7. This embodiment com prises three helical springs 20. The helical springs 20 substan tially extend along the extension direction D. The coils 21 of the spring 20 are loosely connected to one another by control- ling wires 22 which also extend in the extension direction D.

The controlling wires 22 extend through openings 29 provided in the coils 21 of the spring 20. Proximal ends 23 of the springs 20 are fixed to the base member 24 of the instrument 50. Inside or alternatively outside each of the springs 20, a re spective additional fluid-tight tubular sheet 30 is arranged which is closed at a distal end of the spring 20. A single one of the three springs 20 and its additional tubular sheet 30 are shown in Figure 8.

The coils 21 alternatively or additionally also might be con nected to each other by the sheet 30.

By selectively controlling the gas pressures inside the addi tional sheets 30, the direction of further eversion of the sheet 1 can be controlled: Whereas Figures 6 shows a straight state of the extension, a bent state is depicted in Figure 7. In the bent state, the extension direction D changes along the ex tension, as indicated by the bent arrow.

Instead of helical springs, the stabilizing structure of the fourth embodiment shown in Figure 9 contains stabilizing rings 11 which are also connected by controlling wires 22.

The embodiment depicted in Figure 10 does not contain any rotat able positioning wheels but fixed positioning hooks 34 which are designed and arranged such that the inner portion 18 of the sheet 1 is held in position between the driving wheels 5 and the positioning hooks 34.

Figures 11a and lib show a surgical set 60 in accordance with the present invention. The set 60 comprises an insertion instru ment 50 as shown in Figure(s) 1 to 3 as well as a surgical in strument 61 which is provided for extending through the pas sage 19 of the insertion instrument 50. Again for the purpose of simplifying the drawings, the positioning wheels and springs are not shown in Figures 11a and lib.